Method for polishing the balance pivots of a watch



March 21, 1961 H. B. LITTLE 2,975,567

METHOD FOR POLISHING THE BALANCE PIVOTS OF A WATCH Filed May 4, 1960 2Sheets-Sheet 1 INVENTOR. HUGH. B. LITTLE.

MAHONEY MlLfiiAR BO TTYS. BY.

2,975,567 METHOD FOR POLISHING THE BALANCE PIVOTS OF A WATCH Filed May4, 1960 H. B. LITTLE March 21, 1961 2 Sheets-Sheet 2 INVENTOR. HUGH. B.LITTLE BY MAHONY MILLER & RAMBO TWs.

METHGD FOR PGLISHING THE BALANCE PIVOTS OF A WATCH Hugh B. Little,Litties Watch Service, Box 465, Logan, Dhio Filed May 4, me, Set. N5.zasns 6 Claims. c1. 51-281) My invention relates to a method forpolishing the balance pivots of a watch. It has to do, moreparticularly, with a system for use in cleaning and polishing the pivotsor ends of the shaft or balance staff of a watch.

As is well known to jewelers or watch repairmen, the polishing of thepivots on the ends of a watch balance staff is very difficult. Thesepivots range in size from approximately .06 mm. to .14 mm., the .06 mm.size being smaller than a human hair. In order for a watch to runproperly and keep time, the balance pivots must have a high polish andbe properly oiled. At present, it takes a skilled watch repairman aconsiderable length of time to polish the balance pivots due to the timenecessary to set up the tools now commonly used for this purpose and thedifficulty of positioning the pivots relative to the tools and properlyholding the pivots in such a manner as to prevent damage thereto. Thehair spring and/or roller table must, with present polishing methods, beremoved from the balance assembly before polishing the pivots. All ofthe prior art polishing methods are based on the same principle. Theyspin the balance staff and polish the pivots on the shaft by puttingpolish on a piece of steel or wood and holding it against the rotatingshaft. Great care and skill must be used in the polishing operation tosecure a high polish and to keep from bending, breaking, burning orotherwise damaging the pivot.

It is the main object of my invention to provide a polishing method andsystem for use in polishing the pivots of a watch balance staff assemblywhich can be used by a relatively unskilled person to quickly andeffectively polish the pivots.

It is another object of my invention to provide a device for polishingwatch balance pivots which can be used on the balance staff assemblywithout removing the hairspring and/ or roller table therefrom.

A further object of my invention is to provide a polishing device forbalance staff pivots which will effectively polish the pivots withoutdanger of damaging the pivots in any way.

Various other objects will be apparent.

In the accompanying drawings, I have illustrated my polishing device andthe method by which it is used in polishing the balance pivots of awatch.

In these drawings:

Figure 1 is a side elevational view, partly broken away, of thepolishing device.

Figure 2 is an isometric View showing a strip used in making thepolishing loop.

Figure 3 is a transverse sectional View taken along line 33 of Figure 2.

Figure 4 is a view illustrating the twisting of the ends of the strippreparatory to forming the polishing loop.

Figure 5 shows the loop shaped preparatory to inserting in a holdingchuck.

Figure 6 shows the loop inserted in the chuck and a tool being used toshape its exposed or projecting end.

2,975,567 Patented Mar. 21, 1961 Figure 7 is a side elevational view,partly broken away, showing a balance pivot in cooperative relationshipwith the polishing loop.

Figure 8 is an enlarged axial sectional view through the polishing loopand holding chuck showing the action of the loop on the end of thepivot.

With reference to the drawings, in performing my method, I employ adevice which includes a chuck 20 in which the polishing loop 21 ismounted. This chuck 20 is carried by a shaft 22 which is suitablyrotated. For example, the shaft may be driven by any suitable drivingmotor 23, either mechanical or electrical. The loop 21 has an outerconvex surface 25 exposed at the outer end of the chuck 20. It will benoted from Figure 6 that the chuck 26 has a loop-receiving socket 26which is tapered or belled outwardly.

An important feature of this invention is the polishing loop 21. Itconsists of plastic or deformable rubber material which is relativelysoft and which is impregnated with a rouge or other polish material. Informing this loop, a strip 27 of the rubber material is cut from a sheetwhich has been previously impregnated with fine polish material 28. Thisrubber may be of the type commonly known as cushion gum which is a soft,relatively sticky, unvulcanized rubber, and which can be deformed andwill tend to stay in deformed condition. The strip is narrow andelongated as shown in Figure 2.

The next step in preparing the loop is to twist the ends of the strip asindicated in Figure 4. Then. the strip with the twisted ends is foldedback on itself to form a loop 21 as indicated in Figure 5. This loop 21will have a space or slot 30 extending longitudinally thereof betweenthe opposite sides or folds of the loop. The adjacent ends of the loopmay be twisted together to hold it in loop fdrm as indicated in Figure5.

The loop so formed is then forced inwardly into the tapered socket 26 asshown in Figure 6. It will be deformed and compressed during thisforcing action which will narrow the slot 30. The loop will now be heldin the socket by means of friction. With the chuck 2.0 rotating, theouter end of the loop may be formed to provide a convex or sphericalsurface 25. A suitable forming tool is indicated at 31 in Figure 6 andis provided with a concave socket 32 at its outer end. If this tool ispressed against the projecting end of the loop as it is rotated, theconvex surface 25 will be formed. Thus, as shown in Figures 1, 7 and 8,the polishing loop 21 will now be in proper condition to function as thepolishing member. It may be treated from time-to-time with the tool torestore the convex spherical surface.

The balance assembly to be polished is indicated in Figures 1 and 7 andcomprises the balance wheel 40, which has the balance staff 41projecting from opposite sides thereof with the opposed pivots or shafts42 and 43. At one side of the wheel 40 is the roller table 44 and at theother side is the hairspring 45. Neither of these units need be removedduring the polishing operation.

In performing the polishing operation, the chuck 20 is driven at such aspeed to rotate the loop 21 at a suitable speed. The end of the shaft tobe polished, for example, the end 43, is first disposed in contact withthe spherical surface 25. The rotating spherical surface will center therounded end of the shaft with the axis of the chuck and the loop 21.Then the shaft end 43 is forced through the outer or closed end of theloop into the inner slot 36 as shown in Figure 8. After piercing theclosed end of the loop, the staff or assembly 41 is shifted to an anglerelative to the axis of the chuck 20 and the loop 21 as shown in Figure8, the flexible nature of the rubber in the loop permitting this. Ifheld at such an angle, the opposite inner flat surfaces 46 and 47 of theloop 21 will alternately contact the ends of the pivot 43 duringrotation of the loop. This can be noted from a clicking or rubbingaction which occurs at intervals when the end of the shaft is heldwithin the loop in the manner-indicated. This rubbing on polishingaction created in this manner will efiectively polish the pivot endwithout damaging the pivot. After a short interval, the shaft will beshifted to a different angle to polish the other side of the roundedend. This shifting to a different angle is indicated by broken lines inFigure 8.

Thus, itwill be noted that the extreme end of the pivot will beetfectively polished by the rubbing action of the soft rubberimpregnated with the polish or rouge. Furthermore, it will be noted fromFigure 7 that during this polishing operation it is not necessary toremove either the roller table 44 or the hairspring 45. The balancepivot initially will be automatically centered relative to the loop 21and when forced through the material of the loop will be held incentered position. Therefore, it is not necessary for a skilled operatorto perform the polishing operation. The polishing apparatus is alwaysset up ready to use except that it may be desirable to restore theconvex surface 25 of the loop 21 at intervals by means of the tool 31.There is no danger of bending or otherwise distorting, breaking, burningor otherwise damaging the end of the pivot. The polishing loop may beremoved and replaced readily as necessary.

According to the provisions of the patent statutes, the principles ofthis invention have been explained and have been illustrated anddescribed in what is now considered to represent the best embodiment.However, it is to be understood that, within the scope of the appendedclaims, the invention may be practiced otherwise than as specificallyillustrated as described.

Having thus described my invention, what I claim is:

1. The method of polishing the pivot of the balance shaft of a watchwhich comprises impregnating a strip of material with a polishingmaterial, forming the strip into a loop, projecting the pivot end of thebalance shaft through the closed end of the loop at the axis of the loopand holding the shaft at an angle with the end of the pivot in contactwith the inner surface of one side of the loop, and rotating the loopabout its axis.

2. The method of claim 1 in which the angularity of the shaft isreversed after polishing for an interval in the first indicated angularposition.

3. The method ofclaim 1 in which the strip of material is plastic rubberthat is impregnated with a polish ing rouge.

4. The method of claim 3 in which the closed end of the loop is exposedand is of spherical form.

5. The method of polishing the pivot of the balance shaft of a watchwhich comprises forming a strip of polishing material into loop form andprojecting the pivot end of the balance shaft through the closed end ofthe loop and at the axis of the loop, holding the shaft at an angle withthe end of the pivot in the slot between the sides of the loop and inposition to be contacted by said sides, and rotating the loop about itsaxis.

6. The method of claim 5 in which the closed end of the loop is exposedand is of spherical form.

References Cited in the file of this patent UNITED STATES PATENTS596,014 Condon et al. Dec. 21, 1897 2,519,556 Fish Aug. 22, 1950

